The objective of this grant continues to be the improvement of the therapy for children with leukemia and childhood solid tumors by conducting clinical investigation as a member of Childrens Cancer Study Group A (CCSGA) and by ancillary research directly related to the mission of CCSGA. The Childrens Hospital of Los Angeles contributes to all areas of activity of Childrens Cancer Study Group A. Childrens Hospital of Los Angeles is one of the few institutions in the Group conducting pilot studies of new therapies for subsequent group-wide use. With an active program in basic cancer research, Childrens Hospital has an increasingly important influence on CCSGA studies. Investigators at this institution have assumed several roles in leadership in Group Operations. In addition, radiotherapists, surgeons, and pathologists from this institution contribute importantly to the broad activities of CCSGA.